Discovery of a Transient Magnetar: XTE J1810-197

摘要

We report the discovery of a new X-ray pulsar, XTE J1810-197, that was serendipitously discovered on 2003 July 15 by the Rossi X-Ray Timing Explorer (RXTE) while observing the soft gamma repeatex SGR 1806-20. The pulsar has a 5.54 s spin period, a soft X-ray spectrum (with a photon index of nearly equal to 4), and is detectable in earlier RXTE observations back to 2003 January but not before. These show that a transient outburst began between 2002 November 17 and 2003 January 23 and that the source's persistent X-ray flux has been declining since then.